U.S. Pat. No. 5,896,669 discloses an operating substance tank for a portable handheld work apparatus, namely, for an overhead branch cutter. The tank is configured as one piece and has a fill opening for lubricating oil as well as a discharge opening for conducting the lubricating oil to a guide bar having a saw chain running along the periphery thereof. The operating substance tank is connected to an attachment flange for the guide bar. The operating substance tank includes a filter platelet as filter on its discharge opening for the lubricating oil conducted away by a piston pump. In operation, dirt particles are carried into the tank housing when filling the operating substance tank and can lead to a clogging of the discharge opening because of the small filter area which is available.
It is an object of the invention to improve an operating substance tank of the kind described above so that a cloggage of the discharge opening is prevented over a long service life and with a simple configuration.
The operating substance tank of the invention includes an operating substance tank for a portable handheld work apparatus. The operating substance tank includes: a tank housing having a tank interior and including a first housing part; and, a second housing part connected to the first housing part and defining the tank interior conjointly therewith; a filter wall configured as one piece with one of the first and second housing parts; the filter wall partitioning the tank housing into at least first and second spaces; and, the tank including a fill opening and an outflow connection through which the operating substance is drawn.
The operating substance tank is configured of a first housing part and a second housing part. With this configuration, it is possible to configure an internal filter wall on one of the housing parts so that the interior space of the tank is partitioned into two spaces, namely, a dirt or contamination space and a clean space. The filter wall provides a large filter surface which cannot become clogged even after a long time of use.
In a preferred embodiment, the filter wall is made up of lamellae having a gap between each two mutually adjacent ones of the lamellae. The lamellae project out of a wall of one housing part in the direction of the other housing part and terminate preferably in a partition plane between the first and second housing parts. The lamellae lie with their free ends, which face away from the wall, against the second housing part. The cross section of the lamellae is S-shaped or Z-shaped to improve the deposition of dirt thereon. With this constructive measure, dirt particles are better held back during the passage of the operating substance through the filter wall from the dirt space into the clean space. The fill opening is arranged on a wall of the tank housing of the operating substance tank on the dirt space side and the discharge opening is arranged at the clean space side.
It can be practical to configure the first housing part to have an L-shape when viewed in plan and to have a trough-shape when viewed in cross section. The filter wall extends into the tank interior space in an extension of an outer wall of the first housing part. The two housing parts of the operating substance tank are connected to each other with a solid material seal interposed on the partition surfaces of the housing parts. The solid material seal is preferably preformed as one piece. It can be practical to utilize a two-component sealing mass sprayed onto the partition surfaces of a housing part and set.
To minimize mechanical wear of the operating substance tank, the housing parts of the operating substance tank are preferably injection molded from a fiber-reinforced plastic having a correspondingly large wall thickness. The operating substance tank can, however, also be formed of a housing part of plastic and a housing part which is a part of an apparatus housing of a portable handheld work apparatus. If, for example, the operating substance tank functions to make available lubricating oil for a work tool of an overhead branch cutter, then it is practical to arrange the operating substance tank on the side of an attachment flange of the overhead branch cutter in order to obtain a minimized conveyance path to the work tool. This side of the attachment flange lies opposite to the work tool.